This invention relates to magnetic recording, and particularly to transducers therefor.
Known are electromagnetic transducers for writing, reading, and erase-before-writing on magnetic media composed of randomly-oriented oxide particles fixed in a binder, or alternatively on high-coercivity metallic tapes or discs.
Also known are transducers in which a C-shaped, magnetically-permeable core is linked with a prewound electrically-conducting coil for manufacturing economy; but in most of these the transducing gap (at the open side of the C-shape) is too small for threading a prewound coil onto the core, and either the coil must be wound upon the core in the first instance, which can be time-consuming and difficult, or such cores are made in two or more parts, which can be brought together in the final assembly, after being threaded with the prewound coil.
However, every break in the magnetic circuit of the core constitutes, in effect, a low-permeabilty gap that reduces the efficiency of the transducer, i.e., the ratio of the strength of drive signal to flux output.
While a magnetic transducer must have at least one transducing gap, at which the magnetic field bulges outwardly to affect the recording medium, or upon playback, where the core becomes most sensitive to the magnetic fields recorded in the recording medium, it nevertheless follows that any gap that is not needed for transducing, causes a loss of efficiency for the transducer; and this is true even though the parts of a two-part core are pressed tightly together in abutting relation.
Furthermore, most ferrite and other high-permeability, high-saturation and low-coercivity substances of which cores are made in the magnetic recording art, are too brittle for bending without breaking, or are decreased in permeability by the stress of bending, to the degree that the lesser evil, two-part construction, has always been the more acceptable.
Nonetheless, an arrangement in which a prewound coil can be assembled on a high-quality core, without unacceptable, degradation of performance, would always be desirable.
It would also be desirable to adapt such an arrangement to operate a pair of gaps for erasing high-coercivity recording media, and further to associate therewith a record-playback gap and coil in a one-piece-lamination core construction.